Barack Obama is planning to conduct the first major reshuffle of his administration that would see General David Petraeus, the US commander in Afghanistan, take over as head of the CIA and Leon Panetta, the CIA director, become defence secretary.

The Associated Press, which broke the story, reported that Obama would make the announcement on Thursday.

It marks a huge advancement for Petraeus amid speculation that he will stand as Republican candidate for the presidency in 2016. He is already seen as a national hero in the US, credited with turning around the war in Iraq.

That military background plus the CIA job will provide him with a good platform should be opt to run for the White House.

The shifts have been prompted by the long planned retirement of the defence secretary, Robert Gates, who served in the post under George W Bush and was asked by Obama to stay on.

Petraeus was due to leave his post in Afghanistan at the end of the year, having completed his term, and there has been speculation about his next job.

AP, quoting administration and other sources, said the reshuffle would take place in the summer.

The changes will come at an important juncture in the Afghanistan war. US and British forces fought on through the winter for the first time, taking Taliban positions, and they will see how much damage this has done when the Taliban resumes fighting over the spring and summer.

In the near future, Petraeus is scheduled to provide Obama with proposals for a limited number of troop cuts, while Obama is due to announce in July how many US troops will begin to return from Afghanistan.

Panetta, a Democrat, was initially greeted with caution by the CIA but, according to former CIA officials, he has won them over.

In other changes, Ryan Crocker is to become the new ambassador to Afghanistan and Lieutentant-General John Allen will replace Petraeus, according to AP.